1. Field of Invention
The present invention relates to a device for a semiconductor process. More particularly, the present invention relates to a pump ring.
2. Description of Related Art
Chemical Vapor Deposition (CVD) process is a thin film deposition technology for depositing solid product, which is produced from the reactants (usually is gaseous) in the reaction chamber (such as furnace) through the chemical reaction, on the surface of the wafer. CVD process can be widely applied to most kinds of the formation of the thin film such as conductive thin film, semiconductive thin film or dielectric thin film.
However, as for CVD process, the formation of the solid product from the gaseous reactants usually accompanies with producing large number of reactant particles and byproducts. Hence, it is necessary to use air-extracting device to extract the gas from the reaction chamber.
FIG. 1A is a schematic view diagram showing a pump port and a reaction chamber of a conventional CVD apparatus. The CVD apparatus is a sub-Atmosphere Chemical Vapor Deposition (SACVD) apparatus. In addition, FIG. 1B is a cross-sectional view of FIG. 1A along line I-I′. As shown in FIG. 1A and FIG. 1B, one side of a reaction chamber 10 possesses a pump port 12. A pump (not shown) is connected to the reaction chamber 10 through the pump port 12. While the CVD process is performed in the reaction chamber 10, the pump extracts the reactant particles and byproducts from the reaction chamber 10. Moreover, a pump ring 14 is located in the reaction chamber 10, wherein the periphery of the pump ring 14 and the inner wall 11 of the reaction chamber 10 together form a gas-extraction path 18. During the gas extraction, the gas extracted from the inner region 20 of the pump ring 14 by the pump through the gas-extraction path 18 and the pump port 12.
Nevertheless, typically, there is a protrusion 22 located at each side of the pump port 12 at the inner wall 11 of the reaction chamber 10. Therefore, gas-extraction path 18 is shrunk between the protrusion 22 and the pump ring 14. That is, the width d11 of the gas-extraction path 18 is decreased to be the width d12 between the protrusion 22 and the pump ring 14 so that the flow rate of the gas extracted from the inner region 20 of the pump ring 14 is changed to cause the turbulence flow between the protrusion 22 and the pump ring 14. Therefore, the particles are accumulated on the protrusion 22 (that is the accumulation 24 shown in FIG. 1A) so that the reaction chamber 10 is contaminated and the problems of apparatus malfunction and damage of the semi-finished product happened.